1. Field of the Invention
The present invention relates to a transmission device, and more particularly to a transmission device for a two dimensional (2D) image display module to display an image in the 2D image display module.
2. Description of Related Art
With reference to FIGS. 8 and 9, a conventional two dimensional (2D) image display module has a pattern (20) movably sandwiched between a backboard (10) and a lens (30). A transmission device (40) having a cam (41) rotatably mounted on the backboard plate (30) and two arms (42) pivotally connected to the lens (30). Distal ends of each of the two arms (42) are connected to the cam (41) such that when the cam (41) is rotated, the two arms (42) are able to pivot relative to the lens (30). Because the other distal ends of the two arms (42) are engaged with the pattern (20), when the two arms (42) are pivoted, the pattern (20) is moved upward and downward repeatedly. The pattern (20) is thus able to present different pictures backboardd on the angle selected via the lens (30).
It is noted from the conventional transmission device (40) that after the two arms (42) are pivoted, the pattern (20) falls back to its original position by gravity. When the humidity in the air becomes dense, the movement of the pattern (20) becomes sluggish and sometimes may not maintain in its original space, which results in that the observer can not have a very clear image in that the image presenting angle between the pattern (20) and the lens (30) is mis-aligned.
Still further, after the pattern (20) is first inserted between the lens (30) and the backboard (10), calibration of the image presenting angle between the pattern (20) and the lens (30) has to be done manually. That is, the operator has to move around the pattern (20) with the lens (30) fixed or the lens (30) with the pattern (20) moved so as to have the best image presenting angle, which is quite troublesome and inefficient.
To overcome the shortcomings, the present invention intends to provide an improved transmission device to mitigate or obviate the aforementioned problems.